[跟踪报道]——“交通科学的理论与实践”研讨会(WTPTS’04)！

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18日下午第二场特邀报告由香港科技大学的Hong K. Lo（罗康锦）教授宣讲，题目是《Non-equilibrium Dynamic Traffic Assignment》，由北京航天航空大学的黄海军教授主持。

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NON-EQUILIBRIUM DYNAMIC TRAFFIC ASSIGNMENT
Hong K. Lo
(Department of Civil Engineering, Hong Kong University of Science and Technology, Hong Kong)
The principle of dynamic user optimal (DUO) commonly adopted for dynamic traffic assignment (DTA) studies is an idealization. One would not expect this principle to hold perfectly in reality. Indeed, with the more accurate physical queue paradigm, our recent study shows that under certain congested conditions, DUO solutions just do not exist. Recognizing this result, this study provides some initial thinking on developing a framework to accommodate this new finding. Specifically, we introduce the principle of tolerance-based DUO for DTA models with the more realistic physical queue representation, discuss its solution existence and uniqueness through the concept of theoretical gap, develop a solution heuristic, and demonstrate its properties through numerical examples. The results show that solution existence depends on the tolerance of the network users on route swapping. In some cases, the system keeps on evolving without converging to equilibrium. In other words, equilibrium traffic assignment is not an intrinsic property to every network. The generalized notion of “non-equilibrium dynamic traffic assignment” is necessary to describe certain networks with the more realistic physical queue representation.

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香港科技大学的Hong K. Lo（罗康锦）教授的演讲稿－《Non-equilibrium Dynamic Traffic Assignment》

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18日下午第三场特邀报告由香港大学的S .C. Wong（黄仕进）教授宣讲，题目是《A Simultaneous Optimization Formulation of a Discrete/Continuous Transportation System》，由北京航天航空大学的黄海军教授主持。

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A SIMULTANEOUS OPTIMIZATION FORMULATION OF A DISCRETE/CONTINUOUS TRANSPORTATION SYSTEM
S.C. WONG
(Department of Civil Engineering, The University of Hong Kong, Hong Kong)
Y.C. DU
(Department of Road and Traffic Engineering, Tongji University, Shanghai 200092)
H.W. HO
(Department of Civil Engineering, The University of Hong Kong, Hong Kong)
L.J. SUN
(Department of Road and Traffic Engineering, Tongji University, Shanghai 200092)
Consider a city with a highly compact central business district (CBD), and in which commuters? Origins are continuously dispersed. The travel demand is dependent of the total travel cost to the CBD. The transportation system is divided into two layers: major freeways and dense surface streets. Whereas the major freeway network is modeled according to the conventional discrete network approach, the dense surface streets are approximated as a continuum. Travelers to the CBD either travel in the continuum (surface streets) and then exchange to the discrete network (freeways) at an interchange (ramp) before moving to the CBD on the discrete network, or travel directly to the CBD in the continuum. Specific travel cost-flow relationships for the two layers of transportation facilities are considered. We develop a traffic equilibrium model for this discrete/continuous transportation system, in which for a particular origin no traveler can reduce their individual travel cost to the CBD by unilaterally changing routes. The problem is formulated as a simultaneous optimization program with two sub-problems. One sub-problem is a traffic assignment problem from the interchanges to the CBD in the discrete network, and the other is a traffic assignment problem with multiple centers (i.e. the interchange points and the CBD) in the continuous system. A Newtonian algorithm that is based on the sensitivity analyses of the two sub-problems is proposed to solve the resultant simultaneous optimization program. A numerical example is given to demonstrate the effectiveness of the proposed methodology.

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LBSALE[1]LBSALE[这个贴子最后由宋涛在 2005/12/25 03:22am 第 1 次编辑]

香港大学的S .C. Wong（黄仕进）教授的演讲稿－《A Simultaneous Optimization formulation of a Discrete/Continuous Transportation System》

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18日下午第四场特邀报告由北京交通大学的高自友教授宣讲，题目是《交通运输网络复杂性及其相关问题的研究》，由北京航天航空大学的黄海军教授主持。

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交通运输网络复杂性及其相关问题的研究
高自友 吴建军
（北京交通大学交通运输学院系统科学研究所 北京 100044）
黄海军
（北京航空航天大学经济管理学院北京 100083）
按照网络拓扑结构特征划分，我们经常接触到的实际网络有完全规则网络（Completely Regular Networks）、完全随机网络（Completely Random Networks）、小世界网络（Small-world Networks）和无标度网络（Scale-free Networks）。本文系统地对无标度网络的形成、特性和代表性研究成果进行简要总结，重点探讨交通运输网络的复杂性和相关问题，研究了城市公交网络的无标度特性及度分布指数，并以北京市公交网络为例完成了实证分析。进一步，本文从理论上给出了怎样找到公交网络中的枢纽站点这一难题的研究思路、整体框架及求解算法，这是交通运输网络复杂性及其相关问题研究的关键。本文还分别从理论与应用两个层面给出了下一步研究工作的总体思路。通过本文及相关问题的进一步研究，旨在为交通管理部门进行交通运输网络规划、设计、建设和管理
提供科学的研究手段和理论支持。

宋涛

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北京交通大学的高自友教授的演讲稿－《交通运输网络复杂性及其相关问题的研究》

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18日下午第五场特邀报告由南京大学的周晶教授宣讲，题目是《The Generalized Nash Equilibrium Model for Oligopolistic Transit Market With Elastic Demand》，由美国加州大学戴维斯分校的张红军教授主持。

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GENERALIZED NASH EQUILIBRIUM MODEL FOR OLIGOPOLISTIC TRANSIT MARKET WITH ELASTIC DEMAND
Jing Zhou
(School of Management & Engineering, Nanjing University, Nan jing, 210093)
William HK Lam
(Department of Civil & Structural Engineering, The Hong Kong Polytechnic University, Hong Kong)
Benjamin G Heydecker
(Centre for Transport Studies, University College London, London, England)
This paper presents a bilevel transit fare equilibrium model for a deregulated transit system. In the upper-level problem, the transit competition is portrayed as an n-player, non-cooperative game by changing the fare structure of each of a set of transit lines separately so as to maximize the profit of each transit operator within the oligopolistic market. We show that there exists a generalized Nash game between transit operators, which can be formulated as a quasi-variational inequality problem. In the lower-level problem, the passengers’ response to the equilibrium fare structure of the transit operators is represented by the stochastic user equilibrium transit assignment model with elastic OD demand.  As a result, the bilevel transit fare equilibrium problem is presented in the Stackelberg form and solved by a heuristic solution algorithm based on a sensitivity analysis approach. A numerical example is given to illustrate the competition mechanism on the transit network and some useful findings are presented.

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南京大学周晶教授的演讲稿－《The Generalized Nash Equilibrium Model for Oligopolistic Transit Market With Elastic Demand》

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18日下午第四场特邀报告由日本歧阜大学的应江黔教授宣讲，题目是《Some Problems in Traffic Network Equilibrium Analysis》，由美国加州大学戴维斯分校的张红军教授主持。

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Some Problems in Traffic Network Equilibrium Analysis
Jiang Qian Ying
(Faculty of Regional Studies, Gifu University, Japan)
This speech addresses the following problems in equilibrium analysis of traffic networks.  
1.Treatment of road heterogeneity.
There have been extensive researches for treating the heterogeneities of car classes, user classes, etc., in the equilibrium modeling of traffic networks. In the practice of transportation panning and management, the problem of road heterogeneity is also an important problem. It is reported that in practice arterial roads often attracts more traffic than that estimated by equilibrium analysis. The reason seems to be that while in equilibrium analysis drivers are assumed to choose routes of minimum perceived costs (including time and toll), in reality route choice also depends on other characteristics of the roads. Improvement can be made by modeling different kinds of roads as different modes. We will discuss some problems related to road mode choice.
2.Complexity in modeling network equilibrium with non-convexity
When some travel mode exhibits scale economy, equilibrium model is a non-convex one and may be unstable and have multiple equilibria. Computational problems involved in such a complex model will be discussed.
3.The capacity reduction effects of toll collection
In most equilibrium models dealing with road pricing problems, the capacity of road is assumed to be remaining intact by toll collection. With the spread of ETC equipment, this assumption could be true. For practical applications, various means for collecting tolls should be considered. Consequently, there is a need for taking into account the capacity reduction effects of toll collection, in equilibrium modeling for toll policies. A brief investigation into these effects is conducted.

宋涛

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日本歧阜大学的应江黔教授的演讲稿－《Some Problems in Traffic Network Equilibrium Analysis》